app.py

import gradio as gr
import os
import tempfile

from langchain_community.document_loaders import PyPDFLoader
from langchain_text_splitters import RecursiveCharacterTextSplitter
from langchain_community.vectorstores import Chroma
from langchain_community.embeddings import HuggingFaceEmbeddings
from langchain_groq import ChatGroq
from langchain.chains import ConversationalRetrievalChain
from langchain_community.chat_message_histories import ChatMessageHistory
from langchain_core.chat_history import BaseChatMessageHistory

# Persistent vectorstore directory
PERSIST_DIRECTORY = "./chroma_db"

# Store chat histories
chat_histories = {}

def get_session_history(session_id: str) -> BaseChatMessageHistory:
    if session_id not in chat_histories:
        chat_histories[session_id] = ChatMessageHistory()
    return chat_histories[session_id]

def process_files(api_key, model_name, session_id, files, question):
    if not api_key:
        return "Please enter your Groq API key"
    
    # Initialize LLM
    llm = ChatGroq(groq_api_key=api_key, model_name=model_name)
    
    # Process PDFs
    documents = []
    for file in files:
        with tempfile.NamedTemporaryFile(delete=False, suffix=".pdf") as tmp:
            tmp.write(file)
            tmp_path = tmp.name
        
        loader = PyPDFLoader(tmp_path)
        docs = loader.load()
        documents.extend(docs)
        os.unlink(tmp_path)  # Clean up temp file

    # Split and embed
    text_splitter = RecursiveCharacterTextSplitter(chunk_size=5000, chunk_overlap=500)
    splits = text_splitter.split_documents(documents)
    
    embeddings = HuggingFaceEmbeddings(model_name="all-MiniLM-L6-v2")
    vectorstore = Chroma.from_documents(splits, embedding=embeddings, persist_directory=PERSIST_DIRECTORY)
    retriever = vectorstore.as_retriever()

    # Setup RAG chain
    rag_chain = ConversationalRetrievalChain.from_llm(
        llm=llm,
        retriever=retriever,
        return_source_documents=True,
    )

    # Get chat history
    chat_history = get_session_history(session_id)
    
    # Process question
    response = rag_chain({
        "question": question,
        "chat_history": [(msg.content if msg.type == "human" else "Assistant: " + msg.content)
                         for msg in chat_history.messages]
    })

    # Update history
    chat_history.add_user_message(question)
    chat_history.add_ai_message(response["answer"])
    
    # Format response
    output = f"**Assistant:** {response['answer']}\n\n---\n**Chat History:**\n"
    for msg in chat_history.messages[-6:]:  # Show last 3 exchanges
        output += f"{msg.type.capitalize()}: {msg.content}\n"
    
    return output

# Gradio Interface
with gr.Blocks(title="RAG PDF Chat") as demo:
    gr.Markdown("## 📚 Conversational RAG with PDF Uploads")
    
    with gr.Row():
        with gr.Column(scale=1):
            api_key = gr.Textbox(
                label="Groq API Key", 
                type="password",
                placeholder="Enter your API key"
            )
            model = gr.Dropdown(
                label="LLM Model",
                choices=[
                    "qwen-2.5-32b", 
                    "deepseek-r1-distill-llama-70b", 
                    "gemma2-9b-it",
                    "mixtral-8x7b-32768", 
                    "llama-3.3-70b-versatile", 
                    "Gemma2-9b-It"
                ],
                value="mixtral-8x7b-32768"
            )
            session_id = gr.Textbox(
                label="Session ID",
                value="default_session"
            )
            
        with gr.Column(scale=2):
            file_input = gr.File(
                label="Upload PDFs",
                file_types=[".pdf"],
                file_count="multiple"
            )
            question = gr.Textbox(
                label="Your Question",
                placeholder="Ask about the uploaded documents..."
            )
            submit_btn = gr.Button("Submit")
            output = gr.Markdown()
    
    submit_btn.click(
        fn=process_files,
        inputs=[api_key, model, session_id, file_input, question],
        outputs=output
    )

if __name__ == "__main__":
    demo.launch(share=True)